Two goals from Sone Aluko helped Rangers to a victory that ended Dundee United's hopes of denying Motherwell a Champions League qualifying place.
Steven Whittaker curled in a low drive after six minutes before Allan McGregor denied Gary Mackay-Steven an equaliser with a fine save.
Sone Aluko powered past static defenders to fire home twice within 180 seconds to make it 3-0 on 20 minutes.
Jamie Ness on 57 minutes and Alejandro Bedoya in 84 added clinical finishes.
And, although the emphatic win put Rangers eight points clear of Well, it leaves United the same distance behind Stuart McCall's third-top side with only two games remaining.
Salim Kerkar was the surprise choice up front for Rangers along with Aluko, with Andy Little missing through injury and Lee McCulloch only considered fit enough for the bench.
United, unchanged from the side that drew with Hearts, started brightly and a Garry Kenneth free-kick broke through the centre of the defensive wall and Allan McGregor pushed it wide.
From the corner, a Kenneth header across the face of goal was eventually scrambled clear at the back post by Rhys McCabe.
It was McCabe who poked the ball into the path of Whittaker, whose measured grass-cutter curled round a despairing Dusan Pernis and inside the far post from 16 yards.
United were not knocked out of their stride and, when Johnny Russell deflected the ball into the path of Gary Mackay-Steven, only a superb finger-tip save prevented the winger's 15-yard drive finding the net.
Rangers had hardly threatened between the time they opened the scoring and went further ahead.
Kenneth failed to cut out a long ball and, when Kerkar set up Aluko, the striker ghosted past Sean Dillon and fired past Pernis.
A poor John Rankin backpass allowed Kerkar to set Aluko on another run, this time past Kenneth, before driving low into the far corner from 15 yards.
Lee Wallace broke into the United penalty box and only a fine point-blank save from Pernis prevented United being four behind by half-time.
United manager Peter Houston rang the changes at half-time, with youngsters Barry Douglas and Keith Watson on for Kenneth and Mackay-Steven.
The traffic continued towards the United goal, with Aluko forcing Pernis into a near-post save and Maurice Edu mis-hitting straight at the goalkeeper from the resulting corner.
Ness, who had been given a rare start, provided the clinical finish when the ball broke to the midfielder off Aluko after Rangers claimed for handball inside the penalty box.
Edu put substitute Bedoya clear to sidefoot home as Rangers gained revenge for two straight defeats at the hands of the Tannadice outfit.